Errors in my bioperl script. Thanks in advance!

[Lyn Hsiong]

Dear friends:

I have a blast report, and want to extract following information for each result(query): the Query_name, hit_number, name and description of the hit(HSP) with the highest identity.

my bioperl script is:

#!/usr/bin/perl -w
use strict;
use warnings;
use Bio::SearchIO;

if (@ARGV != 2){die "Usage: $0 <BLAST-report-file> <output-file>\n"};

my ($infile,$outfile) = @ARGV;
print "Parsing the BLAST result ...";
my $blast = new Bio::SearchIO(
-format => 'blast',
-file   => $infile);
open (OUT,">$outfile") or die "Cannot open $outfile: $!";

print OUT "query\tNumber of hits\tGreatest identity %\tAccession (identity %)\tDescription (identity %)\n";

while (my $result = $blast->next_result){
   print OUT $result->query_name . "\t";
   print OUT $result->num_hits. "\t";
        if (my $hit = &sort_hit($result)){
                         if (my $hsp=$hit->hsp){
                                        print OUT $hsp->percent_identity. "\t"; 
                                        print OUT $hit->accession. "\t";
                                        print OUT $hit->description. "\n";
                            }                   
           }
    }
 close OUT;
 print " DONE!!!\n";

 sub sort_hit{
                  my $result = shift;
                  my @hits;
                  while (my $hit = $result->next_hit) {
                        push @hits, $hit;
                        }
                  my @hit_sort = sort { $b-> hsp ->percent_identity * 100 <=> $a-> hsp ->percent_identity * 100 } @hits;
                  $result->rewind;
                  my $flag=0;
                  my $temp_hit;
                  while (my $hit=$result->next_hit){
                        if($flag==0){
                           $temp_hit=$hit;
                     $flag++;
                           }
                  return $temp_hit
                        }
         }

error information:

-------------EXCEPTION: Bio::Root::Exception -------------
MSG: Can't get HSPs: data not collected.
STACK: Error::throw
STACK: Bio::Root::Root::throw /home/xiongtl/Bioperl/dag/lib/perl5/Bio/Root/Root.pm:368
STACK: Bio::Search::Hit::GenericHit::hsp /home/xiongtl/Bioperl/dag/lib/perl5/Bio/Search/Hit/GenericHit.pm:688
STACK: main::sort_hit xtl_new.pl:37
STACK: xtl_new.pl:20
-----------------------------------------------------------
Parsing the BLAST result ...

I don't know what does it mean. Please give me some clues, all your words are welcome!


NOTE:
BTW, my bioperl version is 1.6.1, I use blastx 2.2.27+.
My blast report(-outfmt 0) have many queries and each query have many hits(against nr database), so each hit maybe also have several HSPs.

[Torst]

Do you mean $hit->next_hsp instead of $hit->hsp ?

[Lyn Hsiong]

Do you mean $hit->next_hsp instead of $hit->hsp ?

Thanks for your reply!
I tried the $hit->next_hsp before, but running the script still informed me the same error. However, today I have just reruned the script, both $hit->next_hsp and $hit->hsp are ok! They both outputed the first hit for each result. I don't know why. So I tried different sort rules as follows:

# my @hit_sort = sort { $b-> hsp ->hsp_length <=> $a-> hsp ->hsp_length } @hits;
# my @hit_sort = sort { $b-> hsp ->percent_identity * 100 <=> $a-> hsp ->percent_identity * 100 } @hits;
# my @hit_sort = sort { $b-> significance <=> $a-> significance } @hits;
# my @hit_sort = sort { $a-> accession cmp $b-> accession } @hits;

but different sort functions still generate the same output (still the first hit)! It seems that the sub-function does not work at all!
oh, it really troubles me...